A further study of the surface-chemical properties of tooth apatites is proposed to develop a better understanding of basic phenomena that may control the behavior of teeth. A number of investigations are proposed to study the interfacial and dissolution behavior of apatite in aqueous environment. Through such investigations we should be able to obtain the kinds of detailed information about apatite surface chemistry that should help find ways to prevent dental caries and assist in finding suitable restorative adhesive materials. Effect of temperature on fluoride uptake will be correlated with the dissolution and electrical double layer properties. The mechanism of adsorption of organic surface active agents and polymers in tooth pastes, saliva, will be determined and correlated with the interfacial behavior of tooth apatites. The stability of thin aqueous films as measured by ellipsometry will be correlated with contact angle and heat of immersion data to delineate those factors which may control the wetting behavior of tooth apatites. Some of the techniques mentioned above will be used along with adsorption density measurements by gravimetry to study the interaction of certain surface active ingredients of tobacco smoke, such as organic acids and bases, phenols, hydrocarbons, nicotine, etc., with tooth apatites. These studies will determine the influence of constituents in tobacco smoke on the interfacial properties of tooth apatite.